1. Field of Invention
The present invention relates to a novel method for fabricating ultraporous gel monoliths having predetermined mean pore sizes with very narrow distributions of the size of the pores around the means, and to novel ultraporous gel monoliths having predetermined mean pore sizes with very narrow distributions of the size of pores around the mean.
2. Description of the Prior Art
Materials with pore distributions are known in the art and include: (1). chemically etched alkali borosilicate glass (Corning Thirsty Glass) which is made by melting and casting a phase separable glass and then chemically leaching the soluble akali borate phase, leaving a porous boro silica glass matrix. However, it is not possible to produce a narrow range of ultrapore distributions by this method and the glass matrix has residual sodium and boron impurities.; (2). use of high energy particle bombardment of polymers and subsequent chemical etching of the damage tracks to produce mesoporosity, such as, in the filters produced by Millipore Corp. The size of the porosity, and pore size distribution, is limited by this damage track etching method and the matrix material is restricted to polymers.
In contrast to the above state of the art methods of producing controlled pore distributions, the present invention makes it possible to produce controlled pore distributions much smaller in scale and narrower in size range of the pores in an extraordinarily chemically and thermally resistant material such as high purity silica (SiO.sub.2) and also in SiO.sub.2 -Li.sub.2 O-Al.sub.2 O.sub.3 -TiO.sub.2 (Slat) gel compositions which have very low thermal expansion coefficients.